The officials, who spoke on condition they not be named, said the Obama administration last week conveyed its view to other members of the IMF board, which has yet to formally consider the loan.
The U.S. stance does not appear to have had any impact on the government so far in its battle to capture the last redoubt of the Liberation Tigers of Tamil Eelam (LTTE), which have been fighting a 25-year war for a separate ethnic Tamil homeland.
U.S. officials say the government has done too little to protect the civilians in the war zone and has failed to allow in sufficient international aid workers to care for the tens of thousands who have left.
The civilians, estimated by the United Nations to number as many as 50,000, are caught in a tiny LTTE-held area on Sri Lanka's northeast coast, which the military says is down to just 2 square miles (5 square kilometres).
The British and French foreign ministers urged Sri Lanka to implement a humanitarian cease-fire with the rebels to allow tens of thousands of trapped civilians to escape the battle zone. They also urged the rebels to let the civilians leave.
Sri Lanka's ambassador to the United States, Jaliya Wickramasuriya, said the government has generally come to oppose cease-fires, arguing that the rebels have used them in the past to "regroup, rearm, reposition."
